...but seriously, in regards to "no fair", if one wanted to be pedantic about it (but who would?), one could point out that there is an obsolete/archaic noun sense of "fair" - meaning something that is fair or fortunate <fair befall thee -Shakespeare> from which comes the idioms "for fair" and "no fair". I think the former -- e.g., "you caught me for fair" -- is a British idiom, is it not?